MpaR-driven expression of an orphan terminal oxidase subunit supports Pseudomonas aeruginosa biofilm respiration and development during cyanogenesis.
MpaR-driven expression of an orphan terminal oxidase subunit supports Pseudomonas aeruginosa biofilm respiration and development during cyanogenesis.
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铜绿假单胞菌是一种常见的生物膜形成病原体，具有复杂的氧化还原代谢途径。它为有氧呼吸产生四种不同类型的末端氧化酶，对于其中一种 cbb3 型末端氧化酶，它能够产生至少 16 种由部分冗余操纵子编码的亚型。它还产生与呼吸链相互作用的小分子毒力因子，包括毒物氰化物。先前的研究表明氰化物在激活称为 ccoN4 的“孤儿”末端氧化酶亚基基因的表达中发挥作用，并且该产物有助于铜绿假单胞菌的氰化物抗性、生物膜的适应性和毒力，但这一过程的机制尚未阐明。在这里，我们发现调节蛋白 MpaR（预计是磷酸吡哆醛结合转录因子，编码在 ccoN4 的上游）控制 ccoN4 表达以响应内源性氰化物。矛盾的是，我们发现需要氰化物的产生来支持 CcoN4 对生物膜呼吸的贡献。我们鉴定了 ccoN4 的氰化物和 MpaR 依赖性表达所需的回文基序以及共表达的相邻基因座。我们还描述了染色体该区域的调控逻辑。最后，我们鉴定了 MpaR 假定的辅因子结合口袋中的残基，这是 ccoN4 表达所需的。总之，我们的研究结果说明了一种新的情况，其中呼吸毒素氰化物充当信号来控制内源性产生该化合物的细菌中的基因表达。氰化物是血红素铜氧化酶的抑制剂，血红素铜氧化酶是所有真核生物和许多原核生物进行有氧呼吸所必需的。这种速效毒物的来源多种多样，但人们对细菌感知它的机制知之甚少。我们研究了致病菌铜绿假单胞菌对氰化物的调节反应，该细菌产生氰化物作为毒力因子。尽管铜绿假单胞菌具有产生抗氰化物氧化酶的能力，但它主要依赖于血红素铜氧化酶，甚至在产生氰化物的条件下专门产生额外的血红素铜氧化酶蛋白。我们发现蛋白 MpaR 控制铜绿假单胞菌中氰化物诱导基因的表达，并阐明了这种调节的分子细节。 MpaR 包含一个 DNA 结合结构域和一个预计能结合磷酸吡哆醛（维生素 B6）的结构域，磷酸吡哆醛是一种已知会与氰化物自发反应的化合物。这些观察结果提供了对细菌中氰化物依赖性基因表达调节的尚未研究的现象的深入了解。
Pseudomonas aeruginosa is a common, biofilm-forming pathogen that exhibits complex pathways of redox metabolism. It produces four different types of terminal oxidases for aerobic respiration, and for one of these, the cbb3-type terminal oxidases, it has the capacity to produce at least 16 isoforms encoded by partially redundant operons. It also produces small-molecule virulence factors that interact with the respiratory chain, including the poison cyanide. Previous studies had indicated a role for cyanide in activating expression of an “orphan” terminal oxidase subunit gene called ccoN4 and that the product contributes to P. aeruginosa cyanide resistance, fitness in biofilms, and virulence, but the mechanisms underlying this process had not been elucidated. Here, we show that the regulatory protein MpaR, which is predicted to be a pyridoxal phosphate-binding transcription factor and is encoded just upstream of ccoN4, controls ccoN4 expression in response to endogenous cyanide. Paradoxically, we find that cyanide production is required to support CcoN4’s contribution to respiration in biofilms. We identify a palindromic motif required for cyanide- and MpaR-dependent expression of ccoN4 and co-expressed adjacent loci. We also characterize the regulatory logic of this region of the chromosome. Finally, we identify residues in the putative cofactor-binding pocket of MpaR, which are required for ccoN4 expression. Together, our findings illustrate a novel scenario in which the respiratory toxin cyanide acts as a signal to control gene expression in a bacterium that produces the compound endogenously. Cyanide is an inhibitor of heme-copper oxidases, which are required for aerobic respiration in all eukaryotes and many prokaryotes. This fast-acting poison can arise from diverse sources, but mechanisms by which bacteria sense it are poorly understood. We investigated the regulatory response to cyanide in the pathogenic bacterium Pseudomonas aeruginosa, which produces cyanide as a virulence factor. Although P. aeruginosa has the capacity to produce a cyanide-resistant oxidase, it relies primarily on heme-copper oxidases and even makes additional heme-copper oxidase proteins specifically under cyanide-producing conditions. We found that the protein MpaR controls expression of cyanide-inducible genes in P. aeruginosa and elucidated the molecular details of this regulation. MpaR contains a DNA-binding domain and a domain predicted to bind pyridoxal phosphate (vitamin B6), a compound that is known to react spontaneously with cyanide. These observations provide insight into the understudied phenomenon of cyanide-dependent regulation of gene expression in bacteria.
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DOI：
10.1016/j.cub.2015.11.056
发表时间：
2016-01-25
期刊：
Current biology : CB
影响因子：
--
作者：
Hazan R;Que YA;Maura D;Strobel B;Majcherczyk PA;Hopper LR;Wilbur DJ;Hreha TN;Barquera B;Rahme LG
通讯作者：
Rahme LG
影响因子：
3.2
作者：
Arai, Hiroyuki;Kawakami, Takuro;Ishii, Masaharu
通讯作者：
Ishii, Masaharu
影响因子：
3.6
作者：
Dietrich, Lars E. P.;Price-Whelan, Alexa;Newman, Dianne K.
通讯作者：
Newman, Dianne K.
影响因子：
2.8
作者：
CASTRIC, PA
通讯作者：
CASTRIC, PA
影响因子：
6.4
作者：
Broderick, Kate E.;Chan, Adriano;Boss, Gerry R.
通讯作者：
Boss, Gerry R.